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<h2><a name="SECTION0038210000000000000000"></a><a name="msvcrt-files"></a>
<br>
36.2.1 File Operations 
</h2>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-5807' xml:id='l2h-5807' class="function">locking</tt></b>(</nobr></td>
  <td><var>fd, mode, nbytes</var>)</td></tr></table></dt>
<dd>
  Lock part of a file based on file descriptor <var>fd</var> from the C
  runtime.  Raises <tt class="exception">IOError</tt> on failure.  The locked region
  of the file extends from the current file position for <var>nbytes</var>
  bytes, and may continue beyond the end of the file.  <var>mode</var> must
  be one of the <tt class="constant">LK_<var>*</var></tt> constants listed below.
  Multiple regions in a file may be locked at the same time, but may
  not overlap.  Adjacent regions are not merged; they must be unlocked
  individually.
</dl>

<p>
<dl><dt><b><tt id='l2h-5808' xml:id='l2h-5808'>LK_LOCK</tt></b></dt>
<dd>
<dt><b><tt id='l2h-5814' xml:id='l2h-5814'>LK_RLCK</tt></b></dt><dd>
  Locks the specified bytes. If the bytes cannot be locked, the
  program immediately tries again after 1 second.  If, after 10
  attempts, the bytes cannot be locked, <tt class="exception">IOError</tt> is
  raised.
</dd></dl>

<p>
<dl><dt><b><tt id='l2h-5809' xml:id='l2h-5809'>LK_NBLCK</tt></b></dt>
<dd>
<dt><b><tt id='l2h-5815' xml:id='l2h-5815'>LK_NBRLCK</tt></b></dt><dd>
  Locks the specified bytes. If the bytes cannot be locked,
  <tt class="exception">IOError</tt> is raised.
</dd></dl>

<p>
<dl><dt><b><tt id='l2h-5810' xml:id='l2h-5810'>LK_UNLCK</tt></b></dt>
<dd>
  Unlocks the specified bytes, which must have been previously locked. 
</dd></dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-5811' xml:id='l2h-5811' class="function">setmode</tt></b>(</nobr></td>
  <td><var>fd, flags</var>)</td></tr></table></dt>
<dd>
  Set the line-end translation mode for the file descriptor <var>fd</var>.
  To set it to text mode, <var>flags</var> should be <tt class="constant">os.O_TEXT</tt>;
  for binary, it should be <tt class="constant">os.O_BINARY</tt>.
</dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-5812' xml:id='l2h-5812' class="function">open_osfhandle</tt></b>(</nobr></td>
  <td><var>handle, flags</var>)</td></tr></table></dt>
<dd>
  Create a C runtime file descriptor from the file handle
  <var>handle</var>.  The <var>flags</var> parameter should be a bit-wise OR of
  <tt class="constant">os.O_APPEND</tt>, <tt class="constant">os.O_RDONLY</tt>, and
  <tt class="constant">os.O_TEXT</tt>.  The returned file descriptor may be used as a
  parameter to <tt class="function">os.fdopen()</tt> to create a file object.
</dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-5813' xml:id='l2h-5813' class="function">get_osfhandle</tt></b>(</nobr></td>
  <td><var>fd</var>)</td></tr></table></dt>
<dd>
  Return the file handle for the file descriptor <var>fd</var>.  Raises
  <tt class="exception">IOError</tt> if <var>fd</var> is not recognized.
</dl>

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